Jim,
It sounds to me that your disagreement is based only on the potential
magnitude of the import?
-Chris
Jim Hendler <hendler@cs.umd.edu>
09/18/2002 11:11 AM
To: Christopher Welty/Watson/IBM@IBMUS, www-webont-wg@w3.org
cc:
Subject: Re: LANG: owl:ontology
At 9:49 AM -0400 9/18/02, Christopher Welty wrote:
>Jim,
>
>In your example below, that the builder of URI2 may not have "intended"
>for all of URI1 to be loaded when importing URI1:foo is too bad. One of
>the most common and (I think) important reasons to build a million-node
>graph around a set of symbols to to ensure those symbols are used
>correctly, and to prevent them from being used incorrectly. The ontology
>helps to enforce that the intended meaning is maintained.
>
>If someone wants to import just one symbol from my ontology, then they
>have to get all of my ontology so that they get all the constraints and
>inter-relationships that help clarify the meaning of that symbol wrt
>others. I *don't care* if that's what the user intended - that's what
I,
>the designer of the ontology, intended: dont misuse my symbols!
>
>If this isn't enforced, then borrowing symbols from other ontologies is
>meaningless and serves no purpose. There is nothing to gain from using
>URI1:foo if you aren't getting all of the ontology around URI1:foo - you
>may as well just make up your own symbol in URI2, because that's all it
>is. If you are borrowing URI1:foo because "you mean the same thing",
then
>importing the whole ontology that enforces that meaning should have no
bad
>consequence.
>
>Of course ontologies can always be built in a modular way so that if
there
>is a small subset of the symbols that can be exported idependently of
>others (a top level ontology would be one kind of example) then they are
>all in a smaller ontology that is imported, but that is more of an
>engineering issue.
>
>-Chris
Chris, what can I say except I can't disagree more (but am willing to
look for compromise).
Here's real world experience - one of my students wanted to put on
her web page that she had a stuffed penguin on top of her monitor.
She eventually created the following in her ontology
>:isOnTopOf a rdfs:Property;
> rdfs:Domain cyc:ExistingObject;
> rdfs:Range cyc:ExistingObject.
>
>:Penguin a daml:Class;
> rdfs:subClassOf cyc:Bird.
>
in her instances information she asserted
>:penguin1 a our:Penguin;
> our:isOnTopOf :mymonitor.
>
So she has linked her stuff into CYC in some sense, but it clear to
me that I must be able to read her ontology and use it without having
to bring in the entirety of the HUGE cyc graph.
Now, we can get into a deep philosophical issue - do we want to say
she intended to include all the semantics of open cyc (answer: she
said "no" :->) or more importantly, should the CYC folks be saying by
packaging it all together it is all of nothing. But what I'm after
is that she found something useful, it made it easy for her to
express what she wanted on the Semantic Web, and I believe strongly
(my drop dead issue) that we want to encourage this kind of use (see
my article at http://www.cs.umd.edu/~hendler/AgentWeb.html which has
some suggested use cases for ontology extension, modification,
linking, etc).
In short, I see this as a use case that drives what Peter said:
At 10:40 AM -0400 9/18/02, Peter F. Patel-Schneider wrote:
>
>As far as I can see the only viable route is to be able to use resources
>without committing to anything related to that resource. To commit to
>something in some other ontology/document, use imports.
--
Professor James Hendler hendler@cs.umd.edu
Director, Semantic Web and Agent Technologies 301-405-2696
Maryland Information and Network Dynamics Lab. 301-405-6707
(Fax)
Univ of Maryland, College Park, MD 20742 240-731-3822
(Cell)
http://www.cs.umd.edu/users/hendler